package bjtuoj;

import java.util.Arrays;
import java.util.Scanner;

/**
 * ClassName: Homework_4_F
 * Description:
 * date: 2021-12-09 15:39
 *
 * @author liyifan
 */
public class Homework_4_F {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        int m = scanner.nextInt();
        int[] a = new int[n + 1];
        int[] b = new int[300];
        for (int i = 1;i <= n;i++) {
            a[i] = scanner.nextInt();
        }
        for (int i = 1;i <= m;i++ ) {
            int x = scanner.nextInt();
            b[x]++;
        }
        Arrays.sort(a, 1, n + 1);
        for (int i = 1;i <= n;i++) {
            for (int j = a[i] - 1;j >= 1;j--) {
                if (b[j] != 0) {
                    b[j]--;
                    m--;
                    break;
                }
            }
        }
        System.out.printf("%d", m);
    }
}
